The pathogenesis, molecular biology, immunology, natural history, and therapy of human herpes virus infections are being investigated. Immunocompetent and immuno deficient patients with a wide range of herpes virus infections have been identified, followed clinically, diagnosed by virus isolation, studied immunologically and treated with systemic antiviral chemotherapy (adenine Arabinoside or acyclovir) when appropriate. A major effort to study the molecular biology and latency of varicella zoster virus DNA has been initiated. Thermal elution studies, DNA hybridizations, restriction endonuclease analysis, and electron microscopy have been utilized and are shedding light on the structure of the viral DNA.